Derivative Instruments (Change in Fair Value of Derivatives Included in the Consolidated Statement of Operations) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Derivative Instruments, Gain (Loss) [Line Items]
Change in fair value of derivatives	$ 39,099	$ (23,024)	$ (34,966)	$ (54,124)
Change in fair value of embedded derivatives	284,303	(219,601)	550,160	(168,388)
Call Options [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Change in fair value of derivatives	40,394	(20,141)	(30,357)	(49,361)
2015 Notes Hedges [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Change in fair value of derivatives	0	(3,942)	0	(3,375)
Interest Rate Swap [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Change in fair value of derivatives	(982)	827	(3,626)	(934)
Interest Rate Caps [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Change in fair value of derivatives	(313)	232	(983)	(454)
Fixed Index Annuities - Embedded Derivatives [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Change in fair value of embedded derivatives	199,917	(334,481)	379,632	(404,358)
Other Changes in Difference Between Policy Benefit Reserves Computed Using Derivative Accounting Vs. Long-Duration Contracts Accounting [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Change in fair value of embedded derivatives	84,386	118,822	170,528	239,345
2015 Notes Embedded Conversion Derivative [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Change in fair value of embedded derivatives	$ 0	$ (3,942)	$ 0	$ (3,375)